# The car brakes sharply, blocking the wheels. If the coefficient of friction between the tires and the road is 0.5

The car brakes sharply, blocking the wheels. If the coefficient of friction between the tires and the road is 0.5 and the distance traveled by the car to a stop is 40 meters, then what speed did the car have before braking?

To find the speed of the presented car before braking, we use the equality: μ * m * g = Ffr (friction force) = m * a = m * Vn ^ 2 / 2S, whence we express: Vn = √ (2S * μ * g).

Constants and variables: S – the path of the presented car to the stop (S = 40 m); μ – coefficient. friction between tires and road (μ = 0.5); g – acceleration due to gravity (g ≈ 10 m / s2).

Calculation: Vн = √ (2S * μ * g) = √ (2 * 40 * 0.5 * 10) = 20 m / s.

Answer: Before braking, the presented vehicle had a speed of 20 m / s.

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